ccan/io: implement debug.

Now a simple flag, with an external toggle (no compile time DEBUG
define required).  But it's completely synchronous.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

ccan/io/_info

@@ -133,6 +133,7 @@ int main(int argc, char *argv[])
 		return 1;
 
 	if (strcmp(argv[1], "depends") == 0) {
+		printf("ccan/container_of\n");
 		printf("ccan/list\n");
 		printf("ccan/tal\n");
 		printf("ccan/time\n");

ccan/io/backend.h

@@ -25,6 +25,9 @@ struct io_listener {
 /* One connection per client. */
 struct io_conn {
 	struct fd fd;
+	bool debug;
+	/* For duplex to save. */
+	bool debug_saved;
 
 	/* always or closing list. */
 	struct io_conn *list;
@@ -44,7 +47,7 @@ void del_listener(struct io_listener *l);
 void backend_new_closing(struct io_conn *conn);
 void backend_new_always(struct io_conn *conn);
 void backend_new_plan(struct io_conn *conn);
-
+void remove_from_always(struct io_conn *conn);
 void backend_plan_done(struct io_conn *conn);
 
 void backend_wake(const void *wait);

ccan/io/io.c

@@ -10,6 +10,7 @@
 #include <assert.h>
 #include <unistd.h>
 #include <fcntl.h>
+#include <ccan/container_of/container_of.h>
 
 void *io_loop_return;
 
@@ -80,6 +81,7 @@ struct io_conn *io_new_conn_(const tal_t *ctx, int fd,
 	conn->finish = NULL;
 	conn->finish_arg = NULL;
 	conn->list = NULL;
+	conn->debug = false;
 
 	if (!add_conn(conn))
 		return tal_free(conn);
@@ -116,12 +118,9 @@ static struct io_plan *set_always(struct io_conn *conn,
 							  void *),
 				  void *arg)
 {
-	plan->next = next;
-	plan->next_arg = arg;
 	plan->status = IO_ALWAYS;
-
 	backend_new_always(conn);
-	return plan;
+	return io_set_plan(conn, plan, NULL, next, arg);
 }
 
 struct io_plan *io_always_(struct io_conn *conn,
@@ -138,9 +137,7 @@ struct io_plan *io_always_(struct io_conn *conn,
 		plan = io_get_plan(conn, IO_OUT);
 
 	assert(next);
-	set_always(conn, plan, next, arg);
-
-	return plan;
+	return set_always(conn, plan, next, arg);
 }
 
 static int do_write(int fd, struct io_plan *plan)
@@ -161,18 +158,13 @@ struct io_plan *io_write_(struct io_conn *conn, const void *data, size_t len,
 {
 	struct io_plan *plan = io_get_plan(conn, IO_OUT);
 
-	assert(next);
-
 	if (len == 0)
 		return set_always(conn, plan, next, arg);
 
 	plan->u1.const_vp = data;
 	plan->u2.s = len;
-	plan->io = do_write;
-	plan->next = next;
-	plan->next_arg = arg;
 
-	return plan;
+	return io_set_plan(conn, plan, do_write, next, arg);
 }
 
 static int do_read(int fd, struct io_plan *plan)
@@ -201,11 +193,8 @@ struct io_plan *io_read_(struct io_conn *conn,
 
 	plan->u1.cp = data;
 	plan->u2.s = len;
-	plan->io = do_read;
-	plan->next = next;
-	plan->next_arg = arg;
 
-	return plan;
+	return io_set_plan(conn, plan, do_read, next, arg);
 }
 
 static int do_read_partial(int fd, struct io_plan *plan)
@@ -227,8 +216,6 @@ struct io_plan *io_read_partial_(struct io_conn *conn,
 {
 	struct io_plan *plan = io_get_plan(conn, IO_IN);
 
-	assert(next);
-
 	if (maxlen == 0)
 		return set_always(conn, plan, next, arg);
 
@@ -236,11 +223,8 @@ struct io_plan *io_read_partial_(struct io_conn *conn,
 	/* We store the max len in here temporarily. */
 	*len = maxlen;
 	plan->u2.vp = len;
-	plan->io = do_read_partial;
-	plan->next = next;
-	plan->next_arg = arg;
 
-	return plan;
+	return io_set_plan(conn, plan, do_read_partial, next, arg);
 }
 
 static int do_write_partial(int fd, struct io_plan *plan)
@@ -262,8 +246,6 @@ struct io_plan *io_write_partial_(struct io_conn *conn,
 {
 	struct io_plan *plan = io_get_plan(conn, IO_OUT);
 
-	assert(next);
-
 	if (maxlen == 0)
 		return set_always(conn, plan, next, arg);
 
@@ -271,11 +253,8 @@ struct io_plan *io_write_partial_(struct io_conn *conn,
 	/* We store the max len in here temporarily. */
 	*len = maxlen;
 	plan->u2.vp = len;
-	plan->io = do_write_partial;
-	plan->next = next;
-	plan->next_arg = arg;
 
-	return plan;
+	return io_set_plan(conn, plan, do_write_partial, next, arg);
 }
 
 static int do_connect(int fd, struct io_plan *plan)
@@ -319,11 +298,7 @@ struct io_plan *io_connect_(struct io_conn *conn, const struct addrinfo *addr,
 	if (errno != EINPROGRESS)
 		return io_close(conn);
 
-	plan->next = next;
-	plan->next_arg = arg;
-	plan->io = do_connect;
-
-	return plan;
+	return io_set_plan(conn, plan, do_connect, next, arg);
 }
 
 struct io_plan *io_wait_(struct io_conn *conn,
@@ -340,14 +315,10 @@ struct io_plan *io_wait_(struct io_conn *conn,
 	else
 		plan = io_get_plan(conn, IO_OUT);
 
-	assert(next);
-
-	plan->next = next;
-	plan->next_arg = arg;
-	plan->u1.const_vp = wait;
 	plan->status = IO_WAITING;
+	plan->u1.const_vp = wait;
 
-	return plan;
+	return io_set_plan(conn, plan, NULL, next, arg);
 }
 
 void io_wake(const void *wait)
@@ -355,11 +326,11 @@ void io_wake(const void *wait)
 	backend_wake(wait);
 }
 
-static void do_plan(struct io_conn *conn, struct io_plan *plan)
+static int do_plan(struct io_conn *conn, struct io_plan *plan)
 {
 	/* Someone else might have called io_close() on us. */
 	if (plan->status == IO_CLOSING)
-		return;
+		return -1;
 
 	/* We shouldn't have polled for this event if this wasn't true! */
 	assert(plan->status == IO_POLLING);
@@ -367,12 +338,12 @@ static void do_plan(struct io_conn *conn, struct io_plan *plan)
 	switch (plan->io(conn->fd.fd, plan)) {
 	case -1:
 		io_close(conn);
-		break;
+		return -1;
 	case 0:
-		break;
+		return 0;
 	case 1:
 		next_plan(conn, plan);
-		break;
+		return 1;
 	default:
 		/* IO should only return -1, 0 or 1 */
 		abort();
@@ -414,7 +385,7 @@ struct io_plan *io_close(struct io_conn *conn)
 	conn->plan[IO_IN].u1.s = errno;
 	backend_new_closing(conn);
 
-	return &conn->plan[IO_IN];
+	return io_set_plan(conn, &conn->plan[IO_IN], NULL, NULL, NULL);
 }
 
 struct io_plan *io_close_cb(struct io_conn *conn, void *arg)
@@ -439,10 +410,85 @@ int io_conn_fd(const struct io_conn *conn)
 	return conn->fd.fd;
 }
 
-struct io_plan *io_duplex(struct io_plan *in_plan, struct io_plan *out_plan)
+void io_duplex_prepare(struct io_conn *conn)
+{
+	assert(conn->plan[IO_IN].status == IO_UNSET);
+	assert(conn->plan[IO_OUT].status == IO_UNSET);
+
+	conn->debug_saved = conn->debug;
+	conn->debug = false;
+}
+
+struct io_plan *io_duplex_(struct io_plan *in_plan, struct io_plan *out_plan)
 {
+	struct io_conn *conn;
+
 	/* in_plan must be conn->plan[IO_IN], out_plan must be [IO_OUT] */
 	assert(out_plan == in_plan + 1);
 
+	/* Restore debug. */
+	conn = container_of(in_plan, struct io_conn, plan[IO_IN]);
+	conn->debug = conn->debug_saved;
+
+	/* Now set the plans again, to invoke sync debug. */
+	io_set_plan(conn,
+		    out_plan, out_plan->io, out_plan->next, out_plan->next_arg);
+	io_set_plan(conn,
+		    in_plan, in_plan->io, in_plan->next, in_plan->next_arg);
+
 	return out_plan + 1;
 }
+
+struct io_plan *io_set_plan(struct io_conn *conn, struct io_plan *plan,
+			    int (*io)(int fd, struct io_plan *plan),
+			    struct io_plan *(*next)(struct io_conn *, void *),
+			    void *next_arg)
+{
+	struct io_plan *other;
+
+	plan->io = io;
+	plan->next = next;
+	plan->next_arg = next_arg;
+	assert(plan->status == IO_CLOSING || next != NULL);
+
+	if (!conn->debug)
+		return plan;
+
+	if (io_loop_return) {
+		io_debug_complete(conn);
+		return plan;
+	}
+
+	switch (plan->status) {
+	case IO_POLLING:
+		while (do_plan(conn, plan) == 0);
+		break;
+	/* Shouldn't happen, since you said you did plan! */
+	case IO_UNSET:
+		abort();
+	case IO_ALWAYS:
+		/* If other one is ALWAYS, leave in list! */
+		if (plan == &conn->plan[IO_IN])
+			other = &conn->plan[IO_OUT];
+		else
+			other = &conn->plan[IO_IN];
+		if (other->status != IO_ALWAYS)
+			remove_from_always(conn);
+		next_plan(conn, plan);
+		break;
+	case IO_WAITING:
+	case IO_CLOSING:
+		io_debug_complete(conn);
+	}
+
+	return plan;
+}
+
+void io_set_debug(struct io_conn *conn, bool debug)
+{
+	conn->debug = debug;
+}
+
+void io_debug_complete(struct io_conn *conn)
+{
+}

ccan/io/io.h

@@ -432,11 +432,16 @@ struct io_plan *io_connect_(struct io_conn *conn, const struct addrinfo *addr,
  *
  * static struct io_plan *read_and_write(struct io_conn *conn, struct buf *b)
  * {
- *	return io_duplex(io_read(conn, b->in, sizeof(b->in), io_close_cb, b),
- *			 io_write(conn, b->out, sizeof(b->out), io_close_cb, b));
+ *	return io_duplex(conn,
+ *			 io_read(conn, b->in, sizeof(b->in), io_close_cb, b),
+ *			 io_write(conn, b->out, sizeof(b->out), io_close_cb,b));
  * }
  */
-struct io_plan *io_duplex(struct io_plan *in_plan, struct io_plan *out_plan);
+#define io_duplex(conn, in_plan, out_plan) \
+	(io_duplex_prepare(conn), io_duplex_(in_plan, out_plan))
+
+struct io_plan *io_duplex_(struct io_plan *in_plan, struct io_plan *out_plan);
+void io_duplex_prepare(struct io_conn *conn);
 
 /**
  * io_wait - leave a plan idle until something wakes us.
@@ -575,4 +580,38 @@ void *io_loop(struct timers *timers, struct list_head *expired);
  * Sometimes useful, eg for getsockname().
  */
 int io_conn_fd(const struct io_conn *conn);
+
+/**
+ * io_set_debug - set synchronous mode on a connection.
+ * @conn: the connection.
+ * @debug: whether to enable or disable debug.
+ *
+ * Once @debug is true on a connection, all I/O is done synchronously
+ * as soon as it is set, until it is unset or @conn is closed.  This
+ * makes it easy to debug what's happening with a connection, but note
+ * that other connections are starved while this is being done.
+ *
+ * See also: io_debug_complete()
+ *
+ * Example:
+ * // Dumb init function to set debug and tell conn to close.
+ * static struct io_plan *conn_init(struct io_conn *conn, const char *msg)
+ * {
+ *	io_set_debug(conn, true);
+ *	return io_close(conn);
+ * }
+ */
+void io_set_debug(struct io_conn *conn, bool debug);
+
+/**
+ * io_debug_complete - empty function called when conn is closing/waiting.
+ * @conn: the connection.
+ *
+ * This is for putting a breakpoint onto, when debugging.  It is called
+ * when a conn with io_set_debug() true can no longer be synchronous:
+ * 1) It is io_close()'d
+ * 2) It enters io_wait() (sychronous debug will resume after io_wake())
+ * 3) io_break() is called (sychronous debug will resume after io_loop())
+ */
+void io_debug_complete(struct io_conn *conn);
 #endif /* CCAN_IO_H */

ccan/io/io_plan.h

@@ -52,7 +52,51 @@ struct io_plan {
 	union io_plan_arg u1, u2;
 };
 
-/* Helper to get a conn's io_plan. */
+/**
+ * io_get_plan - get a conn's io_plan for a given direction.
+ * @conn: the connection.
+ * @dir: IO_IN or IO_OUT.
+ *
+ * This is how an io helper gets a plan to store into; you must call
+ * io_done_plan() when you've initialized it.
+ *
+ * Example:
+ * // Simple helper to read a single char.
+ * static int do_readchar(int fd, struct io_plan *plan)
+ * {
+ *	return read(fd, plan->u1.cp, 1) <= 0 ? -1 : 1;
+ * }
+ *
+ * struct io_plan *io_read_char_(struct io_conn *conn, char *in,
+ *				 struct io_plan *(*next)(struct io_conn*,void*),
+ *				 void *arg)
+ * {
+ *	struct io_plan *plan = io_get_plan(conn, IO_IN);
+ *
+ *	// Store information we need in the plan unions u1 and u2.
+ *	plan->u1.cp = in;
+ *
+ *	return io_set_plan(conn, plan, do_readchar, next, arg);
+ * }
+ */
 struct io_plan *io_get_plan(struct io_conn *conn, enum io_direction dir);
 
+/**
+ * io_set_plan - set a conn's io_plan.
+ * @conn: the connection.
+ * @plan: the plan
+ * @io: the IO function to call when the fd is ready.
+ * @next: the next callback when @io returns 1.
+ * @next_arg: the argument to @next.
+ *
+ * If @conn has debug set, the io function will be called immediately,
+ * so it's important that this be the last thing in your function!
+ *
+ * See also:
+ *	io_get_plan()
+ */
+struct io_plan *io_set_plan(struct io_conn *conn, struct io_plan *plan,
+			    int (*io)(int fd, struct io_plan *plan),
+			    struct io_plan *(*next)(struct io_conn *, void *),
+			    void *next_arg);
 #endif /* CCAN_IO_PLAN_H */

ccan/io/poll.c

@@ -88,17 +88,21 @@ bool add_listener(struct io_listener *l)
 	return true;
 }
 
-void backend_new_closing(struct io_conn *conn)
+void remove_from_always(struct io_conn *conn)
 {
-	/* Already on always list?  Remove it. */
-	if (conn->list) {
-		struct io_conn **p = &always;
+	struct io_conn **p = &always;
 
-		while (*p != conn)
-			p = &(*p)->list;
+	while (*p != conn)
+		p = &(*p)->list;
 
-		*p = conn->list;
-	}
+	*p = conn->list;
+}
+
+void backend_new_closing(struct io_conn *conn)
+{
+	/* Already on always list?  Remove it. */
+	if (conn->list)
+		remove_from_always(conn);
 
 	conn->list = closing;
 	closing = conn;

ccan/io/test/run-01-start-finish-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-01-start-finish.c"

ccan/io/test/run-01-start-finish.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64001"
+#else
 #define PORT "65001"
 #endif
 static int expected_fd;
@@ -21,6 +23,9 @@ static void finish_ok(struct io_conn *conn, int *state)
 
 static struct io_plan *init_conn(struct io_conn *conn, int *state)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(*state == 0);
 	(*state)++;
 	expected_fd = io_conn_fd(conn);

ccan/io/test/run-02-read-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-02-read.c"

ccan/io/test/run-02-read.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64002"
+#else
 #define PORT "65002"
 #endif
 
@@ -24,6 +26,9 @@ static void finish_ok(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 

ccan/io/test/run-03-readpartial-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-03-readpartial.c"

ccan/io/test/run-03-readpartial.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64003"
+#else
 #define PORT "65003"
 #endif
 
@@ -25,6 +27,9 @@ static void finish_ok(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 

ccan/io/test/run-04-writepartial-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-04-writepartial.c"

ccan/io/test/run-04-writepartial.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64004"
+#else
 #define PORT "65004"
 #endif
 
@@ -25,6 +27,9 @@ static void finish_ok(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 	io_set_finish(conn, finish_ok, d);

ccan/io/test/run-05-write-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-05-write.c"

ccan/io/test/run-05-write.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64005"
+#else
 #define PORT "65005"
 #endif
 
@@ -25,6 +27,9 @@ static void finish_ok(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 	io_set_finish(conn, finish_ok, d);

ccan/io/test/run-06-idle.c

@@ -9,7 +9,9 @@
 #include <sys/stat.h>
 #include <fcntl.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64006"
+#else
 #define PORT "65006"
 #endif
 

ccan/io/test/run-07-break-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-07-break.c"

ccan/io/test/run-07-break.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64007"
+#else
 #define PORT "65007"
 #endif
 
@@ -30,6 +32,9 @@ static void finish_ok(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 

ccan/io/test/run-09-connect-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-09-connect.c"

ccan/io/test/run-09-connect.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64009"
+#else
 #define PORT "65009"
 #endif
 
@@ -33,6 +35,9 @@ static struct io_plan *connected(struct io_conn *conn, struct data *d2)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 	io_close_listener(l);

ccan/io/test/run-12-bidir-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-12-bidir.c"

ccan/io/test/run-12-bidir.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64012"
+#else
 #define PORT "65012"
 #endif
 
@@ -34,6 +36,9 @@ static struct io_plan *rw_done(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 
@@ -42,7 +47,8 @@ static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 	memset(d->wbuf, 7, sizeof(d->wbuf));
 	io_set_finish(conn, finish_ok, d);
 
-	return io_duplex(io_read(conn, d->buf, sizeof(d->buf), rw_done, d),
+	return io_duplex(conn,
+			 io_read(conn, d->buf, sizeof(d->buf), rw_done, d),
 			 io_write(conn, d->wbuf, sizeof(d->wbuf), rw_done, d));
 }
 

ccan/io/test/run-14-duplex-both-read-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-14-duplex-both-read.c"

ccan/io/test/run-14-duplex-both-read.c

@@ -8,7 +8,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64014"
+#else
 #define PORT "65014"
 #endif
 
@@ -37,12 +39,16 @@ static struct io_plan *make_duplex(struct io_conn *conn, struct data *d)
 {
 	d->state++;
 	/* Have duplex read the rest of the buffer. */
-	return io_duplex(io_read(conn, d->buf+1, sizeof(d->buf)-1, end, d),
+	return io_duplex(conn,
+			 io_read(conn, d->buf+1, sizeof(d->buf)-1, end, d),
 			 io_write(conn, d->wbuf, sizeof(d->wbuf), end, d));
 }
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 

ccan/io/test/run-15-timeout.c

@@ -8,7 +8,9 @@
 #include <stdio.h>
 #include <unistd.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64015"
+#else
 #define PORT "65015"
 #endif
 
@@ -36,6 +38,9 @@ static struct io_plan *no_timeout(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 

ccan/io/test/run-16-duplex-test-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-16-duplex-test.c"

ccan/io/test/run-16-duplex-test.c

@@ -8,7 +8,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64016"
+#else
 #define PORT "65016"
 #endif
 
@@ -34,6 +36,9 @@ static struct io_plan *io_done(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 
@@ -43,7 +48,8 @@ static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 
 	io_close_listener(d->l);
 
-	return io_duplex(io_read(conn, d->buf, sizeof(d->buf), io_done, d),
+	return io_duplex(conn,
+			 io_read(conn, d->buf, sizeof(d->buf), io_done, d),
 			 io_write(conn, d->wbuf, sizeof(d->wbuf), io_done, d));
 }
 

ccan/io/test/run-17-homemade-io-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-17-homemade-io.c"

ccan/io/test/run-17-homemade-io.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64017"
+#else
 #define PORT "65017"
 #endif
 
@@ -77,15 +79,15 @@ static struct io_plan *io_read_packet(struct io_conn *conn,
 	pkt->contents = NULL;
 	plan->u1.vp = pkt;
 	plan->u2.s = 0;
-	plan->io = do_read_packet;
-	plan->next = cb;
-	plan->next_arg = arg;
 
-	return plan;
+	return io_set_plan(conn, plan, do_read_packet, cb, arg);
 }
 
 static struct io_plan *init_conn(struct io_conn *conn, struct packet *pkt)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(pkt->state == 0);
 	pkt->state++;
 

ccan/io/test/run-18-errno-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-18-errno.c"

ccan/io/test/run-18-errno.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64018"
+#else
 #define PORT "65018"
 #endif
 
@@ -27,6 +29,9 @@ static void finish_EBADF(struct io_conn *conn, int *state)
 
 static struct io_plan *init_conn(struct io_conn *conn, int *state)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	if (*state == 0) {
 		(*state)++;
 		errno = 100;

ccan/io/test/run-19-always-debug.c

@@ -0,0 +1,2 @@
+#define DEBUG_CONN
+#include "run-19-always.c"

ccan/io/test/run-19-always.c

@@ -6,7 +6,9 @@
 #include <sys/wait.h>
 #include <stdio.h>
 
-#ifndef PORT
+#ifdef DEBUG_CONN
+#define PORT "64019"
+#else
 #define PORT "65019"
 #endif
 
@@ -30,6 +32,9 @@ static struct io_plan *write_buf(struct io_conn *conn, struct data *d)
 
 static struct io_plan *init_conn(struct io_conn *conn, struct data *d)
 {
+#ifdef DEBUG_CONN
+	io_set_debug(conn, true);
+#endif
 	ok1(d->state == 0);
 	d->state++;
 	io_set_finish(conn, finish_ok, d);